I 


CM   ^'-" 
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The  Need  of  Quantitativ 


in  Applied  Geology 


By  CHARLES  H.  WHITE 


ods 


MAY  £9  1930 


An  address  given  before  the  San  Francisco  Section  of 
the  American  Institute  of  Mining-  and  Metallurgical  Engineers 
on  March  6,  1921,  and  published  in  the  Mining  and  Scientific 
Press  April  30,  1921. 


Additional  copies  of  this  paper  may  be  obtained  by  addressing  the 
author  at  788  Mills  Building,  San  Francisco. 


The  Need  of  Quantitative  Methods 
in  Applied  Geology 

By  CHARLES  H.  WHITE 


Geology,  like  the  other  sciences,  can  be  of  service  only  to  the 
degree  that  its  methods  are  exact.  In  other  words,  the  useful- 
ness of  the  science  is  measured  by  the  precision  of  its  technique. 

The  science  of  geology  had  its  origin  in  the  union  of  the 
speculations  of  philosophy  with  the  small  body  of  facts  regard- 
ing rocks,  ores,  and  other  minerals  accumulated  in  the  course 
of  the  winning  of  the  metals  and  the  useful  minerals  ;  a  union 
of  the  a  priori  with  the  empirical.  These  two  methods  of 
attack  have  come  down  to  us  from  the  time  that  man  began  to 
make  history,  and,  indeed,  both  are  still  extant,  although 
happily  no  longer  of  equal  authority.  According  to  the  Scrip- 
tures, while  Tubal  Cain  was  beating  out  useful  implements  of 
brass,  cosmic  philosophers  were  expounding  how  "the  land 
was  separated  from  the  great  deep  ' '  and  how  ' '  the  mountains 
were  brought  forth." 

In  consequence  of  the  production  of  silver  from  the  mines  at 
Laurium,  which  have  been  worked  frorn  pre-historic  time,  Attic 
philosophers  were  able  to  sit  in.ili^r^x^ademic.lsiiades  and  dis- 
course on  the  origin  of  fossils",  volcanoes,  and  earthquakes.1 

Throughout  the  ages  there  -"have  been^  '&$*3tw6  classes  of 
contributors  to  the  stream  of  human  knowledge.  The  one,  out 
of  the  operations  of  the  brain  alone,  by  sheer  power  of  thought, 
elucidates  all  manner  of  phenomena,  whether  terrestrial  or  celes- 
tial, and  all  of  man's  relations  to  his  environment,  whether 
temporal  or  eternal ;  the  other,  working  not  only  with  the  brain 
but  with  the  hands  as  well,  carefully  measures  and  tests  and 
proves  by  experiment — as  far  as  it  is  possible  to  do  so — the 
truth  or  falsity  of  the  hypothetical  creations  of  the  imagination. 

1  While  the  mines  at  Laurium  were  the  property  of  the  State,  their  proceeds  were  dis- 
tributed among  the  citizens  after  the  ordinary  expenses  of  government  were  paid. 


731205 


The  two  methods  of  approach  are  well  illustrated  by  a  con- 
troversy related  by  President  Goodnow  of  Johns  Hopkins  Uni- 
versity, which  took  place  between  two  men,  on  the  deck  of 
a  steamer  ploughing:  through  the  Gulf  Stream  at  night,  regard- 
ing the  origin  of  the  phosphorescent  glow  following  the  trail  of 
the  propeller.  One  of  them  was  a  dignified  devotee  of  pure 
thought,  and  the  other  a  grubbing  student  of  zoology.  When 
the  zoologist  maintained  that  this  fascinating  trail  of  light  was 
due  to  myriads  of  a  minute  form  of  animal  life,  the  reverend 
gentleman  replied  in  great  astonishment  that  such  a  cause  had 
never  occurred  to  him  although  he  had  given  the  subject  a 
great  deal  of  thought. 

All  the  physical  sciences  have  come  through  the  same  strug- 
gle. After  centuries  of  thegropings  of  alchemy,  chemistry  had 
its  birth  with  the  discovery  of  oxygen  and  the  laws  of  constant 
and  multiple  proportions,  less  than  a  hundred  and  fifty  years 
ago.  A  little  more  than  a  decade  later  James  Hutton,  a  Scot, 
published  the  first  book  on  geology  that  had  any  semblance  of 
"organized  common  sense,"  to  use  Huxley's  definition  of 
science. 

Geology,  then,  as  a  science,  can  be  said  to  be  only  about  a 
hundred  years  old.  Since  the  days  of  Hutton  there  has  been  a 
gradual  emergence  from  the  chaos  of  hypothetical  dreams,  al- 
though in  comparison  with  other  sciences  the  rise  seems  extra  - 
ordinairly  slow.  Perhaps  the  reason  for  this  lag  behind  the 
other  applied  sciences  is  justifiable.  Its  problems,  to  us,  seem 
more  profound.  .  Dataware  sornetimes  difficult  and  expensive 
to  obtain.  The  physician  can  easily  test  his  theory,  for  he  can 
lay  open  his  subject  and  view  the  results  of  his  experiment ;  but 
erosion  and  the  miner  combined  have  only  scratched  the  epider- 
mis of  the  earth.  The  constitution  of  the  sun  is  probably  better 
known  than  that  of  the  interior  of  the  earth.  Even  the  topog- 
raphy of  the  earth  is  not  so  well  known  as  that  of  the  side  of 
the  moon  which  is  turned  toward  us.  Geology  is  not  slow  in 
propounding  problems,  but  she  waits  for  chemistry,  physics, 
mineralogy,  and  paleontology  to  supply  the  tools  with  which  to 
solve  them. 

In  the  last  twenty  years  geology  has  been  far  outdistanced  by 


the  other  applied  sciences.  Compare,  for  example,  the  brilliant 
step  in  surgery  and  medicine  from  Spanish  War  methods  to 
World  War  methods,  or  the  rejuvenation  of  chemistry  through 
the  discovery  of  radium  and  all  its  hopeful  progeny.  Other 
examples  of  progress,  while  geology  in  comparision  has  slept, 
are  in  locomotion  and  in  the  transmission  of  thought.  In  loco- 
motion the  methods  of  the  early  Egyptians  have  survived  so 
long  that  it  is  only  in  our  day  they  have  given  way  to  the 
electric  car,  the  automobile,  and  the  aeroplane  ;  and  in  the 
transmission  of  thought — I  do  not  refer  to  the  methods  of  Sir 
Oliver  Lodge — we  have  communication  by  wire  and  by  wireless. 

To  illustrate  the  slow  development  of  the  scientific  method 
in  geology,  let  us  take,  for  example,  the  subject  of  vulcanism, 
the  phenomena  of  which,  perhaps,  are  the  most  striking  of  a 
geological  nature  that  interested  early  man  and  that  were  un- 
doubtedly the  most  important  to  those  who  lived  within  the 
danger  zone  of  volcanoes.  In  spite  of  the  general  interest  in 
volcanoes  and  their  very  special  importance  to  large  groups  of 
people,  surprisingly  little  is  known  of  their  origin  or  their 
habits,  and  almost  no  progress  has  been  made  in  foretelling 
their  behavior. 

My  first  experience  with  volcanoes  was  at  Vesuvius  shortly 
after  the  great  eruption  of  April,  1906.  The  lava  had  pushed 
its  way  down  through  the  village  of  Bosco  Trecase,  tearing 
asunder  small  residences,  surrounding  the  larger  buildings,  and 
covering  the  railroad  to  a  depth  of  ten  to  fifteen  feet.  It  had 
only  just  solidified  and  was  still  too  hot  to  walk  upon.  The 
mountain  could  not  be  approached  from  that  side,  being  well 
guarded  by  both  hot  lava  and  a  detachment  of  soldiers.  I 
drove  around  to  the  east  side,  to  the  town  of  Ottajano,  where 
guards  were  not  so  much  in  evidence.  Here  the  volcanic  ash 
and  lapilli  had  fallen  to  a  depth  of  several  feet.  The  great 
weight  of  it  on  the  roofs  had  carried  many  of  them  with  all  that 
was  in  the  house,  including  the  dwellers,  into  the  cellar.  The 
entire  population,  except  a  few  guides  and  guards,  was  wholly 
occupied  in  clearing  the  ash  away  from  the  vines  and  fruit- 
trees,  from  the  streets,  and  from  the  ruined  houses  in  the  effort 
to  recover  their  dead,  so  that  I  was  able  to  slip  out  of  the  town 


unobserved  and  to  climb  unmolested  and  alone  to  the  top  of 
Monte  Somma. 

From  Monte  Somma,  which  is  the  remnant  of  a  greater  pre- 
historic Vesuvius,  I  could  look  across  the  Atrio  del  Cavallo,  a 
distance  of  about  half  a  mile  on  a  level  line,  to  the  active  crater 
of  Vesuvius.  Smoke  and  ashes  were  rising,  now  calmly  and 
majestically,  and  again  violently  and  in  greater  volume.  The 
immense  black  cloud  spreading-  over  the  surrounding-  country, 
and  condensing-,  splashed  the  landscape  with  great  drops  of 
mud.  Such  a  sight  for  the  first  time  is  a  remarkable  stimulus 
to  the  imagination. 

The  material  ejected  from  the  crater  came  down  only  in 
splashes  ;  the  unanswerable  questions  provoked  by  this  awe- 
inspiring  spectacle  came  as  a  deluge.  I  was  oppressed  not  only 
by  my  own  ignorance  but  by  that  of  all  mankind.  Vesuvius 
had  received  the  attention  of  writers  long  before  the  Christian 
era.  Strabo  had  pronounced  it  a  volcano  before  the  time  of 
any  known  eruption  and  while  it  was  still  apparently  extinct. 
The  first  recorded  eruption  was  that  which  destroyed  Pompeii 
in  August  79  A.D.  This  was  observed  by  Pliny  the  younger, 
who,  in  letters  to  Tacitus,  described  certain  of  the  events  in  con- 
siderable detail,  and  in  spite  of  the  1827  years  of  intervening 
study  of  volcanoes  between  his  visit  and  mine,  he  was  appar- 
ently about  as  competent  to  understand  the  phenomena  as  I 
was.  He,  his  mother,  and  his  uncle,  the  elder  Pliny,  were  .liv- 
ing at  Misenum,  where  his  uncle  was  in  command  of  the  fleet. 
Misenum  is  on  a  point  on  the  west  side  of  the  Bay  of  Naples, 
17  miles  west  of  Vesuvius.  In  his  letter  Pliny  writes  :2  "  On 
the  24th  of  August,  about  one  in  the  afternoon,  my  mother 
desired  my  uncle  to  observe  a  cloud  which  appeared  of  a  very 
unusual  size  and  shape.  .  .  .  He  immediately  arose  and 
went  out  upon  a  rising  ground  from  whence  he  might  get  a 
better  sight  of  this  very  uncommon  appearance.  A  cloud  . 
was  ascending,  the  appearance  of  which  I  cannot  give  you  a 
more  exact  description  of  than  by  likening  it  to  that  of  a  pine- 
tree,  for  it  shot  up  to  a  great  height  in  the  form  of  a  very  tall 
trunk,  which  spread  itself  out  at  the  top  into  a  sort  of  branches, 

2  Translation  by  William  Melmoth, 


occasioned,  I  image,  either  by  a  sudden  gust  of  air  that  im- 
pelled it,  the  force  of  which  decreased  as  it  advanced  upwards, 
or  the  cloud  itself  being  pressed  back  by  its  own  weight, 
expanded  in  the  manner  I  have  mentioned ;  it  appeared  some- 
times bright  and  sometimes  dark  and  spotted,  according  as  it 
was  either  more  or  less  impregnated  with  earth  and  cinders. 
This  phenomenon  seemed  to  a  man  of  such  learning  and 
research  as  my  uncle  extraordinary  and  worth  further  looking 
into." 

He  then  described  how  his  uncle,  when  about  to  set  out  in  a 
light  vessel  to  cross  over  to  observe  the  eruption,  gets  a  message 
from  a  friend  that  the  towns  on  the  shore  at  the  foot  of  Vesu- 
vius are  in  great  danger,  changes  his  mind,  orders  the  galleys 
to  put  to  sea,  and  "  what  he  had  begun  from  a  philosophical, 
he  now  carries  out  in  a  noble  and  generous  spirit."  The 
writer  then  depicts  how  as  the  ships  approach  the  mountain 
"  the  cinders,  which  grew  thicker  and  hotter,  fell  into  the  ships 
together  with  pumice-stones  and  black  pieces  of  burning  rock  ; 
they  were  in  danger  too  of  not  only  being  aground  by  the  sud- 
den retreat  of  the  sea  but  also  from  the  vast  fragments  which 
rolled  down  from  the  mountain  and  obstructed  all  the  shore." 

He  follows  with  an  account  of  his  uncle's  landing  at  Stabiae, 
going  for  the  night  to  the  house  of  a  friend,  how  stones  and 
ashes  fell  on  the  houses  at  such  a  rate  that  fearing  they  would 
be  trapped,  they  held  a  consultation  as  to  "  whether  it  would 
be  most  prudent  to  trust  to  the  houses  which  now  rocked  from 
side  to  side  with  frequent  and  violent  concussion  as  though 
shaken  from  their  very  foundations,  or  fly  to  the  open  fields 
where  the  calcined  stones  and  cinders,  though  light  indeed,  yet 
fell  in  large  showers,  and  threatened  destruction.  In  the  choice 
of  dangers  they  resolved  for  the  fields.  .  .  .  They  went  out 
then  having  pillows  tied  upon  their  heads  with  napkins  ;  and 
this  was  their  whole  defense  against  the  storm  of  stones  that 
fell  around  them.  .  .  .  They  thought  proper  to  go  farther 
down  upon  the  shore  to  see  if  they  might  safely  put  out  to  sea, 
but  found  the  waves  still  running  extremely  high  and  boisterous. 
Then  my  uncle  laying  himself  down  upon  a  sail-cloth,  which 


was  spread  for  him,  called  twice  for  some  cold  water,  which  he 
drank,  when  immediately  the  flames,  preceded  by  a  strong-  whiff 
of  sulphur,  dispersed  the  rest  of  the  party,  and  obliged  him  to 
rise.  He  raised  himself  up  with  the  assistance  of  two  of  his 
servants  and  instantly  fell  down  dead,  suffocated,  as  I  conjec- 
ture, by  some  gross  and  noxious  vapor.  ' ' 

At  the  time  of  my  visit  in  1906,  while  standing  on  Monte 
Somma,  I  also  got  a  strong  whiff  of  sulphur  and  found  myself 
conjecturing  about  the  "  gross  and  noxious  vapor." 

Up  to  that  time  gases  from  fumeroles  and  earth- cracks  near 
craters  had  been  analyzed ;  that  is,  we  knew  qualitatively  in 
a  general  way  what  gases  sometimes  escape  in  volcanic  dis- 
tricts ;  but  we  did  not  know,  and  do  not  know  yet,  anything  of 
the  quantity  of  the  various  gases,  including  water  vapor,  that 
is  discharged  through  any  continuous  period  at  the  time  of  an 
eruprion. 

In  1858  Deville  and  Le  Blanc  published  results  of  analyses  of 
gases,  which  indicated  that  the  nature  of  the  emanations  from 
a  volcanic  district  varies  with  the  time  that  elapses  after  the 
beginning  of  an  eruption ;  that  is,  there  is  a  relative  decrease 
of  chlorine  and  sulphur  gases  and  an  increase  of  carbon  di-ox- 
ide ;  but  apparently  no  one  has  tried  to  learn  if  eruptions  can 
be  predicted  by  observing  if  the  reverse  variations  take  place 
as  an  eruption  approaches. 

Upon  my  return  home  I  inquired  of  certain  institutions  organ- 
ized for  research  if  they  would  be  interested  in  the  study  of 
gases  from  craters,  in  taking  lava  temperatures,  etc.  The  Car- 
negie Institution  of  Washington  was  very  much  interested,  and 
since  that  time  it  has  made  some  important  studies  on  volca- 
noes. In  1909,  for  the  first  time,  the  temperature  of  lava  in  a 
crater  was  taken  at  Kilauea.  Three  years  later,  at  the  same 
place,  also  for  the  first  time,  gas  was  withdrawn  from  a  crater 
for  analysis.  Since  that  time  other  volcanic  districts  have  been 
visited  by  members  of  the  staff  of  the  Geophysical  Laboratory 
and  numerous  samples  of  gases  collected  for  analysis  from 
fumeroles  and  quiescent  craters  ;  but  I  would  not  regard  the 
study  of  a  volcano  to  have  been  seriously  undertaken  until  its 


gases  are  sampled  and  analyzed  automatically  and  continuously 
and  the  results  recorded  on  a  dial,  along  with  the  temperature, 
in  the  same  way  that  these  operations  are  carried  out  at  chem- 
ical and  metallurgical  works  and  at  power  plants.  If  we  had 
the  continuous  record  of  the  carbon  di-oxide,  sulphur  di-oxide, 
hydrochloric  acid,  and  water  from  a  few  craters  from  one  erup- 
tion to  the  next,  as  well  as  the  continuous  record  of  tempera- 
ture, no  one  can  predict  what  benefits  might  ensue. 

Naturally  enough  the  expense  of  installing  the  necessary 
equipment  for  such  work  discourages  the  undertaking.  Auto- 
matic, or  mechanical,  gas-analyzers  would  be  required  and  also 
the  necessary  pipe  to  connect  the  apparatus  with  the  volcanic 
vent  through  which  the  gases  could  be  drawn  continously,  and 
the  pipe  would  have  to  be  made  of  fused  silica  or  other  refrac- 
tory material. 

After  centuries  of  apparently  no  progress,  a  beginning  has 
been  made  at  last.  It  was  about  1912  that  Ferret,  by  the  use 
of  the  microphone,  in  an  Italian  volcanic  district  was  able  to 
predict  an  eruption  and  give  timely  warning  of  its  approach. 
In  1914  I  found  that  a  concrete  base  was  being  placed  in  the 
Vesuvius  observatory  for  the  installation  of  the  first  seismograph 
at  that  station,  and  Professor  Malladra,  the  director,  showed  me 
a  temperature  curve  of  the  fumerole  in  the  crater  of  Vesuvius 
that  he  had  made  through  a  period  of  several  years,  proving 
that  the  temperature  was  uniformly  higher  in  winter  than  in 
summer  ;  the  higher  temperature  in  winter  being  due,  as  he 
said,  to  the  water  added  by  the  increased  rainfall  of  winter. 

Philosophical  speculation  long  dominated  in  the  field  of  geol- 
ogy. Aristotle  taught  that  earthquakes  were  caused  by  the 
generation  of  wind  within  the  earth  under  the  influence  of  the 
warmth  of  the  sun  and  the  internal  heat.  From  Aristotle  to 
Agricola  is  a  leap  of  nearly  nineteen  centuries  ;  but  we  find 
Agricola,  who  was  the  author  of  the  first  serious  work  on 
mineralogy,  as  late  as  1546  urging  his  mining  students  to  study 
philosophy  so  that  they  might  "  discern  the  origin,  cause,  and 
nature  of  subterranean  things  ;  for  they  will  be  able  to  dig  out 
the  veins  easily  and  advantageously  and  obtain  more  abundant 


8 

results  from  their  mining-."  3  Even  Gottlob  Werner,  who  fol- 
lowed soon  after  Agricola,  and  for  about  forty  years  was  the 
great  geological  enthusiast  at  the  Freiberg  Mining-  Acadamy, 
and  died  only  about  a  hundred  years  ago,  taught  that  all  rocks, 
crystaline  as  well  as  non-crystaline,  were  precipitated  from  the 
primeval  ocean  and  followed  in  the  same  succession  the  world 
over.  He  also  believed  that  volcanoes  resulted  from  the  burn- 
ing of  subterranean  beds  of  coal. 

In  the  field  of  economic  geology,  as  well  as  in  other  branches 
of  the  subject,  the  development  of  the  quantitative  method  has 
been  slow,  but  even  with  his  limited  technique  the  economic 
geologist  has  been  able  to  assist  the  miner  in  following  his  ore 
through  the  vicissitudes  of  folding  and  faulting  where  the 
deposit  was  bedded  or  in  sheet-like  form.  He  has  also  been  able 
to  locate  artesian  water  and  to  pick  out  favorable  spots  for  pools 
of  petroleum.  With  the  aid  of  the  magnetometer,  he  has  been 
able  to  find  and  map  concealed  bodies  of  magnetite  and  also  to 
locate  non-magnetic  bodies  of  iron  ore  where  these  bodies  occu- 
pied a  certain  definite  relation  to  magnetic  beds  that  were  them- 
selves too  lean  in  magnetite  to  constitute  ore — a  method  very 
successfully  applied  in  Michigan  and  elsewhere.  He  has  been 
able  to  predict  with  tolerable  accuracy  extensions  of  orebodies 
where  mineralization  favors  certain  rocks  in  preference  to 
others,  through  his  ability  to  identify  the  rocks  and  to  deter- 
mine the  structure.  His  services  have  been  in  demand  in  war 
as  well  as  in  peace.  General  Pershing  had  a  geologist  on  his 
staff  in  France,  and  through  this  branch  of  the  service  trenches, 
dugouts,  and  other  earthworks  were  placed  favorably  to  avoid 
troublesome  rock-structures ,  especially  water-bearing  beds .  The 
geologist,  indeed,  is  able  to  assist  in  practically  all  large  under- 
takings that  involve  operations  in  or  on  the  materials  of  the 
earth's  crust.  Tn  agriculture,  war,  water-supply,  fuel-supply, 
road  construction,  and  many  other  branches  of  engineering ; 
in  mineral  production  of  all  kinds,  and  especially  ore  produc- 
tion ;  and  in  his  every  sphere  of  activity,  the  value  of  his  ser- 
vice increases  as  his  methods  approach  quantitative  accuracy. 

3  '  De  Re  Metallica,1  Hoover's  translation. 


As  an  illustration  of  the  advantage  of  the  quantitative  method 
as  applied  to  ore-finding  geology,  let  us  consider  briefly  some 
of  the  criteria  for  judging  croppings  of  disseminated  sulphide 
deposits.  If  erosion  has  brought  the  surface  down  to  or  within 
a  few  feet  of  the  primary  ore,  the  two  important  considerations 
— the  grade  of  the  ore  and  the  size  of  the  deposit — become 
comparatively  simple.  By  a  surficial  examination,  possibly 
with  some  trenching,  the  grade  of  the  ore  and  its  areal  exten- 
sion are  determined  ;  the  depth  only  remains  to  be  ascertained. 
This  resolves  itself,  so  far  as  the  geologist  is  able  to  assist,  into 
a  problem  of  structural  geology. 

But  let  us  suppose  that  oxidized  croppings  of  unknown 
depth  over  a  large  area  are  colored  with  limonite  and  show  a 
marked  amount  of  sericitization,  kaolinization,  or  silicification, 
or  all  three  combined,  what  can  the  geologist  tell  of  the  prob- 
abilities of  ore  below  ?  Let  us  see  what  is  the  status  of  our 
knowledge  on  the  subject. 

The  literature  on  croppings  is  not  extensive  nor  is  it  always 
strictly  scientific.  Two  characteristics  are  usually  dwelt  upon 
as  being  of  greatest  importance  :  the  color  of  the  croppings 
and  the  degree  of  silicification.  We  will  consider  for  a  moment 
the  first  of  these  characteristics,  the  color  of  the  limonite,  and 
take  up  for  comparison  what  current  technical  literature  has  to 
offer  about  Miami  in  this  regard. 

J.  Parke  Channing  states  that  the  cropping  is  stained  red  in 
patches  by  iron  oxide  and  only  occasionally  by  small  green 
copper  stains. 

Ransome  says  that  the  largest  orebodies  at  Miami  ' '  are  not 
often  found  under  those  surface  rocks  that  are  most  vividly 
colored  by  copper  compounds  or  iron  oxides."4 

F.  H.  Probert  states  that  "  at  Ray  and  Miami  the  color  over 
schist  ore  is  pale  chocolate-brown  and  copper  silicate  at  the 
surface."5 

Channing  says  the  cropping  is  red  in  patches  ;  Ransome  that 
the  reddest  ground  is  not  over  the  best  ore ;  and  Probert  that  it 

4  U.  S.  G.  S.  Bull.  529,  paye  186. 

5  'M.  &  S.  P.',    June  17,  1916. 


10 


is  a  pale  chocolate-brown.  While  these  statements  perhaps 
cannot  be  strictly  construed  as  conflicting-,  yet  they  do  not  lead 
unerringly  to  a  conclusion.  It  is  a  very  simple  matter  by  means 
of  the  Maxwell  color-wheel  to  resolve  a  color  into  its  elements 
and  to  determine  precisely  the  percentage  of  each  of  its  com- 
ponents. Practically  all  writers  on  this  subject  regard  the  color 
as  very  important,  yet  they  have  not  considered  it  sufficiently 
important  to  make  strictly  accurate  quantitative  statements 
regarding  it. 

By  a  careful  study  of  the  surface  at  Miami  it  has  been  found 
that  the  croppings  of  the  disseminated  sulphides  may  be  divided 
into  three  areas,  each  having-  its  own  peculiar  color.  On  the 
south  side  of  the  Pinto  fault — the  up-thrust  side  of  the  fault — 
the  color  is  lighter,  almost  suggesting:  pink,  with  an  occasional 
copper  stain.  North  of  the  fault,  but  still  over  the  orebody, 
the  color  is  more  distinctly  red.  Still  farther  north,  beyond  the 
orebody  and  over  pyritic  ground,  the  red  is  still  deeper  in  color. 
In  an  effort  to  establish  a  quantitative  basis  on  which  to  compare 
these  colors,  I  analyzed  the  colors  of  several  specimens  from 
these  two  areas,  respectively  over  ore  and  over  pyrite.  I  found 
that  in  both  areas  the  color  was  composed  of  red,  yellow,  black, 
and  white  ;  but  there  was  on  the  average  a  considerably  higher 
percentage  of  red,  yellow,  and  white  over  the  orebody  than  over 
the  poor  ground ;  in  fact,  there  was  twice  as  much  white  in  the 
color  over  the  orebody  as  in  that  over  poor  ground,  and  four 
times  as  much  black  in  the  poor  ground  as  in  the  good  ground. 
While  no  definite  and  important  conclusions  can  be  drawn  from 
these  few  tests,  even  in  one  district,  yet  the  trial  suggests  the 
possibilities  of  the  method  and  leads  us  to  wonder  what  might 
be  the  result  if  we  could  have  such  tests  made  on  large  numbers 
of  samples  from  many  disseminated  deposits. 

As  to  the  second  characteristic,  opinion  seems  to  be  practi- 
cally unanimous  that  croppings  of  disseminated  orebodies  are 
more  highly  silicious  than  similiar  croppings  of  disseminated 
sulphides  poor  in  copper ;  but  quantitative  statements  on  the 
subject,  I  believe,  have  never  been  published.  As  an  effort  in 
this  direction,  I  examined  carefully  with  the  hand-glass  about 


11 


90  samples  from  Miami,  about  one-third  from  over  the  ore  and 
two-thirds  from  the  pyritic  non-orebearing  ground,  and  esti- 
mated as  accurately  as  I  could  the  content  in  quartz,  having-  in 
mind  that  only  the  mineralization  quartz  was  important.  As  a 
result  of  this  test  I  found  that  there  was  on  an  average  nearly 
twice  as  much  quartz  in  samples  from  the  orebearing  ground  as 
in  those  from  the  non-orebearing  ground.  A  number  of  deter- 
minations on  other  characteristics  of  croppings  were  made,  but 
the  examples  given  are  sufficient  to  indicate  that  this  is  a  prom- 
ising: field  for  investigation.  The  importance  of  such  quantita- 
tive studies  is  apparent  when  we  realize  that  it  was  probably 
the  lack  of  such  a  technique  that  resulted  in  failure  of  the 
Miami  company  to  obtain  possession  of  what  is  now  Inspiration 
ground. 

These  examples  of  the  very  inadequate  study  of  two  charac- 
teristics of  croppings  show  how  little  is  really  known  about 
croppings,  and  suggest  the  importance  of  applying-  every  pos- 
sible method  of  measurement  to  all  the  variable  characters  of 
croppings  to  determine,  if  possible,  the  significance  of  the 
variations. 

As  a  possible  aid  to  those  who  may  wish  to  study  croppings 
in  a  quantitative  way  there  is  outlined  below  a  method  of  map- 
ping and  note-taking,  which  I  have  used  with  considerable 
satisfaction.  By  this  method  the  degree  of  development  of 
numerous  and  oft-repeated  characteristics  may  be  recorded 
rapidly  (and  in  a  roughly  quantitative  way)  in  a  small  space. 
Suppose,  for  example,  it  is  desired  to  record  at  frequent  inter- 
vals the  following  characteristics  : 

1.  Texture  of  the  rock,  degree  to  which  it  is  preserved. 

2.  Fractures,  distance  apart. 

3.  Kaolinization,  intensity. 

4.  Silicification,  general,  intensity, 

5.  Quartz  in  veinlets,  distance  apart. 

6.  Limonite,  soaked  into  kaolin,  paint  on  joints,  pseudomor- 
phous  after  pyrite. 

7.  Limonite  in  veinlets,  distance  apart. 


12 

8.  Limonite,  disseminated,  frequency. 

9.  Sericitization,  intensity. 

10.  Copper  stain  in  kaolin,  intensity. 

11.  Copper  stain  in  veinlets,  distance  apart. 

By  this  method  each  characteristic  is  represented  by  a  line 
which  cuts  a  side  of  a  small  square  or  other  polygon,  always  in 
the  same  position  with  reference  to  a  beginning-  corner.  The 
degree  to  which  the  characteristic  is  developed  is  represented 
by  the  depth  to  which  its  line  penetrates  the  polyg-on.  If  the 
line  is  wholly  within  the  polyg-on,  the  charateristic  represented 
by  it  is  little  developed.  If  the  line  cuts  the  periphery,  the 
characteristic  is  moderately  developed ;  and  if  the  line  lies  out- 
side the  polyg-on,  it  is  highly  developed.  The  first  character 
recorded  is  represented  by  a  line  set  diag-onally  at  the  begin- 
ning: corner  of  the  polygon  ;  all  other  lines  are  set  at  right  angles 
to  the  sides  of  the  figure,  and  are  read  clock- wise,  each  line,  by 
its  position,  always  representing-  the  same  characteristic  in  any 
one  district.  The  system  may  be  changed  from  one  district  to 
another  by  using:  the  lines  to  represent  other  characteristics 
which  it  is  desired  to  record. 


For  example,  this    symbol     Ji1    T.     means,  that 


1.  The  texture  of  the  rock  is  partly  gone. 

2.  The  fractures  are,  say,  from  ]/2  to  2  in.  apart. 

3.  It  is  partly  kaolinized. 

4.  Slight  silicification. 

5.  Quartz  veinlets  from  1/2  to  2  in.  apart. 

6.  Limonite  soaked  into  kaolin. 

7.  Limonite  veinlets  more  than,  say,  2  in.  apart. 

8.  Limonite  disseminated  in  specks,  say,  25  per  square  inch. 

9.  A  litte  sericite. 

10.  A  little  copper  stain. 

11.  No  veinlets  of  copper. 

By  this  method  notes  that  would  require  half  a  page  in  the 
ordinary  note-book  may  be  recorded  in  less  than  a  quarter-inch 


13 


square.  This  has  been  found  useful,  not  only  in  recording 
information  on  surface  maps,  but  also  in  note-taking"  under- 
ground. From  these  notes,  maps  may  be  made  to  show  areas 
on  which  the  various  characteristics  predominate,  singly,  or  in 
any  desired  combination. 

When  we  consider  how  much  is  still  unknown  regarding-  the 
occurrence  of  ores  it  seems  truly  surprising  that  the  service  of 
the  geologist  is  so  greatly  in  demand.  This  demand,  however, 
is  too  often  the  last  resort.  In  too  many  instances  the  geologist 
is  only  permitted  to  serve  as  the  oxygen-tank  to  the  expiring 
enterprise. 

Several  years  ago,  but  long  after  the  principles  of  artesian 
water  were  well  undestood,  one  of  our  largest  Southern  cities 
hopefully  sank  what  they  expected  to  be  an  artesian  well  near 
the  centre  of  the  great  granite  laccolith  upon  which  the  city  was 
built.  Several  years  later  the  governing  board  of  a  leading 
uuiversity,  ignoring  its  department  of  geology,  which  was  kept  in 
ignorance  of  the  proceeding,  spent  a  large  sum  of  money  sinking 
for  artesian  water  in  a  glacial  sand  plain  that  lies  on  an  impos- 
sible complex  of  ancient  crystalline  rocks.  The  humblest  assist- 
ant in  the  department,  receiving  the  princely  salary  of  f  500 
per  annum,  would  have  lost  his  position  had  he  not  known 
enough  to  avert  such  a  loss  of  money  if  his  advice  had  been 
asked. 

In  the  coalfield  of  southern  West  Virginia,  where  the  struct- 
ure is  unusually  flat,  a  mining  company  wishing  to  open  a  coal 
seam  on  that  side  of  the  mountain  opposite  the  place  of  discov- 
ery of  the  coal,  sent  their  engineer  with  a  wye  level  to  run  an 
exact  level  around  the  mountain.  After  many  days  of  cutting 
out  thick  underbrush  the  line  was  completed,  an  adit  was  made 
through  the  heavy  talus,  but  no  coal  was  found.  A  member  of 
the  U.  S.  Geological  Survey  came  that  way  and  discovered  near 
the  base  of  the  mountain  an  excellent  horizon- marker  (a  thin  bed 
of  fossiliferous  limestone),  which,  traced  around  the  mountain, 
revealed  an  unexpected  flexure  in  the  beds — a  deformation 
entirely  unsuspected  by  the  engineer.  In  this  instance  the 


14 


geolgist  accomplished  in  a  few  hours  what  the  engineer  had 
failed  to.  do  after  several  days. 

The  preventable  waste  in  exploitation  is  enormous,  even  with 
the  present  inadequate  technique  of  the  geologist.  Often  do 
we  find,  for  example,  mountains  and  ridges  shot  through  with 
barren  tunnels  for  the  purpose  of  tapping  at  great  depths  the 
downward  extension  of  paltry  outcropping  veins  at  the  top, 
which  could  have  been  proved  worthless  by  a  little  serious  work 
on  the  outcrop.  Some  of  this  waste  can  be  charged  to  the 
over-enthusiastic  and  visionary  prospector ;  some  to  the  pro- 
moter who  must  have  the  appearance  of  important  work  con- 
tinued so  as  to  postpone  the  fatal  day,  while  he  sells  stock ;  but 
much,  unfortunately,  is  chargeable  to  organizations  composed 
of  men  of  honor  and  intelligence.  Not  only  should  this  waste 
be  stopped,  but  much  of  that  which  is  now  conceded  to  be  un- 
avoidable could  also  be  prevented  by  improvement  in  the  tech- 
nique of  geology  through  properly  directed  research  ;  and  this 
research  to  be  effective  must  give  careful  attention  to  every 
minute  detail. 


"" 


OVERDUe  «'.00    ON    THE    SEV^rOURTH 

~  >i  TH    DAY 


Stockton,  Calif. 

PAT.  JAN.  21.  1908 


731205 


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